Whitehouse K17 mods...

[Bazbro_imp]

Are you adding fuel in any method? Removing the cats will lean out the mixture...and these bikes run lean enough as is.

I'm not removing the catalysers, PD.
The Wyvern paperwork shows a picture of a catalyser along with the exhaust pics, which I'm assuming is fitted, because the paperwork also includes a Certificate (of Conformity?). It's all in Japanese at the moment, but I'll translate it tomorrow.

It's just the O2 Sensors that I'm not fitting, as per the Forum discussion link. I know it might be controversial, but I've read the evidence and, as it's VERY common to remove these Sensors (on a great many different 'bikes. with corresponding smoother running) I think it worth doing.
(And I've just noticed that I mis-wrote "dissembling" instead of "disassembling" in my write-up - a very important difference! I can't edit it out now...) Red Face